Beef Research Articles

Applying Systems Thinking to Sustainable Beef Production Management: Modeling-Based Evidence for Enhancing Ecosystem Services

We used systems thinking (ST) to identify the critical components of beef cattle production through the lens of ecosystem services (ES), offering a holistic approach to address its adverse externalities. We identified eight critical feedback loops in beef production systems: (i) grazing and soil health, (ii) manure management and soil fertility, (iii) feed efficiency and meat production, (iv) water use and soil moisture, (v) cultural services and community engagement, (vi) energy use, (vii) carbon sequestration and climate regulation, and (viii) environmental impact. Our analysis reveals how these interconnected loops influence each other, demonstrating the complex nature of beef production systems. The dynamic hypothesis identified through the loops indicated that improved grazing and manure management practices enhance soil health, leading to better vegetation growth and cattle nutrition, which, in turn, have a positive impact on economic returns to producers and society, all of which encourage the continuation of interlinked beef and ecosystem stewardship practices. The management of beef production ES using ST might help cattle systems across the globe to contribute to 9 of the 17 different United Nations’ Sustainable Development Goals, including the “zero hunger” and “climate action” goals. We discussed the evaluation framework for agrifood systems developed by the economics of ecosystems and biodiversity to illustrate how ST in beef cattle systems could be harnessed to simultaneously achieve the intended environmental, economic, social, and health impacts of beef cattle systems. Our analysis of the literature for modeling and empirical case studies indicates that ST can reveal hidden feedback loops and interactions overlooked by traditional practices, leading to more sustainable beef cattle production outcomes. ST offers a robust framework for enhancing ES in beef cattle production by recognizing the interconnectedness of ecological and agricultural systems, enabling policymakers and managers to develop more effective and sustainable strategies that ensure the long-term health and resilience of humans and ES.

Study on the Carcass Traits, Meat Quality, and Nutritional Attributes of Six Kinds of Jiangxi Local Breeds Cattle

The purpose of this study is to explore the carcass traits, meat quality, and nutritional attributes of local yellow cattle (Guangfeng, Ji’an, and Jinjiang) and buffalo (Poyanghu, Xiajiang, and Xinfeng mountain) in Jiangxi Province, and compare the differences among different breeds. The results showed that the dressing percentage, net meat percentage, and meat–bone ratio of Jinjiang cattle were highest, and that Jinjiang cattle had the best meat production performance. Regarding meat quality, the pH24h value of all breeds was at normal level, and no dark-cutting beef was produced. Poyanghu buffalo and Xinfeng mountain buffalo had higher redness (a*) values, and Guangfeng cattle had the best water retention and tenderness. The intermuscular fat of yellow cattle breeds was higher than that of buffalo breeds; Poyanghu buffalo had the highest crude protein content. The composition of amino acids and fatty acids was different among breeds, and the composition of Jiangxi breeds was healthy. The muscle fibers of buffalo breeds are generally smaller and denser than those of yellow cattle breeds. The MyHC-Ⅰ, MyHC-Ⅱa, and MyHC-Ⅱx were the main types of muscle fibers of Jiangxi local breeds, and the proportion varied with different breeds. This work elucidated the carcass characteristics, meat quality, and nutritional attributes of Jiangxi breed cattle to provide a theoretical basis for optimizing the development of beef cattle industry.

Impact of fermented wine lees on gut microbiota and metabolic responses in Guanling crossbred cattle

BackgroundThe addition of wine lees to diets can make up for the deficiencies caused by traditional forages in beef cattle farming. However, the effects of different wine lees ratios on average daily weight, gastrointestinal microbial community structure and metabolites in Guanling crossbred cattle have been rarely studied. This study assessed the effects of feeds containing wine lees on weight gain, gastrointestinal microbial community structure, and metabolites in Guanling crossbred cattle and elucidated the metabolic responses induced by wine lees. Eighteen cows were randomly assigned to receive fed concentrate (C group), feed containing 15% wine lees (group A), or feed containing 30% wine lees (group B) for 60 days.ResultsThe average daily weight gain of group A and group B increased by 76.75% and 57.65%, respectively, compared with group C. Microbial community analysis showed that wine lees increased the abundance of Prevotella_1 in the rumen, decreased the abundance of Ruminococcaceae UCG 011 and Lachnospiraceae_FCS020_group in the rumen, and increased the abundance of Tyzzerella_4, Family_Xlll_AD3011_group, Granulicella, and Eisenbergiella in the cecum. Metabolomics analyses showed that wine lees decreased the concentrations of indole-3-ethanol in the rumen, and complexity cecal metabolism. Notably, linoleic acid metabolism was significantly enriched in both the rumen and cecum. Mantel test analyses indicated that the adverse effects of WL were reduced by stimulating the metabolism of linoleic acid, α-linolenic acid, and tryptophan, and these changes were mediated by intestinal microorganisms. The Guanling cattle cecum was enriched for several unfavorable metabolic pathways when wine lees concentrations reached 30%, which increased the likelihood of intestinal lesions.ConclusionThis study shows that WL supplementation alters gut microbiota and metabolic pathways, improving cattle growth and health. Moderate WL levels (15%) enhance gut health and beneficial pathways (e.g., linoleic and alpha-linolenic acid metabolism). However, higher WL inclusion (30%) may activate adverse pathways, raising the risk of intestinal damage. To maximize benefits and minimize risks, WL levels should be carefully managed.

Folic acid supplementation during fattening period affects growth and nutritional metabolism in Japanese Black beef cattle

The folate requirements for beef cattle have not been established. Therefore, we investigated whether rumen-unprotected folic acid supplementation during the fattening period affects carcass traits and nutritional metabolism in Japanese Black beef cattle. Eighteen Beef cattle aged 16 months were divided into three groups: control, low folic acid supplementation (0.43 g DM/day), and high folic acid supplementation (0.86 g DM/day). Treatment was administered for 12 months. Folic acid supplementation dose-dependently increased serum folate levels, suggesting that supplemental folic acid can be absorbed into the body. Folic acid supplementation dose-dependently decreased serum vitamin B12 levels, while plasma total homocysteine and methylmalonic acid levels—markers for deficiency of folate and/or vitamin B12—were unaffected. Thus, the treatment did not clearly affect the nutritional status of these vitamins. Supplementation increased body weight, with no negative effects on other carcass traits. The levels of insulin-like growth factor 1, retinol, albumin, and some amino acids in serum or plasma were affected by supplementation. These results suggest that rumen-unprotected folic acid supplementation during the fattening period could increase the body weight of Japanese Black beef cattle and the mechanism of action may be related to growth-related hormones and/or the metabolism of some nutrients, including folate.

Addition of Tannin-Containing Legumes to Native Grasslands: Effects on Enteric Methane Emissions, Nitrogen Losses and Animal Performance of Beef Cattle

Extensive cattle production on native grasslands is vital to the sustainability of the South American Pampas, and the inclusion of tannin-containing legumes can increase farm profitability, improve nitrogen (N) use and reduce greenhouse gas (GHG) emissions. This study quantified the effects of adding tannin-containing legumes to native grasslands on enteric methane (CH4) emissions, animal performance and N balance in cattle. A crossover design trial was conducted with 22 beef heifers under two treatments: native grassland (NG) and native grassland with the addition of Lotus uliginosus and L. angustissimus (NG+L). The results showed that forage mass disappearance was similar between treatments; however, 54% of the forage disappearance in the NG+L corresponded with legumes, indicating that the heifers in this treatment consumed a better-quality diet. While individual CH4 emissions were similar between treatments, heifers grazing the NG+L showed a higher average daily gain (ADG) and lower emissions intensity than heifers grazing NGs (0.25 vs. 0.58 g CH4/g ADG, p < 0.05). Additionally, they also ingested 20% more N and were more efficient in its utilization. Incorporating tannin-containing legumes into native grasslands can improve animal productivity and N use efficiency while reducing the intensity of enteric CH4 emissions.

Antioxidant potential of olive leaf (<i>Olea europaea</i> L.) sustainable extracts evaluated <i>in vitro</i> and minced beef meat

In this work, by using water steam only, two antioxidant extracts were obtained from olive leaves (Olea europaea L.), a by-product of olive oil chain. Olive leaf extracts (OLEs) were tested as such (water extract: WE) and partially purified with ethyl acetate (ethyl acetate [EA] extract). Total phenols were 7.4 mg/mL and 3.8 mg/mL in WE and EA final solutions, respectively, evidencing a different composition by high-performance liquid chromatography analysis. Both extracts were evaluated in vitro in comparison to pure hydroxytyrosol (Hy). A 2,2-diphenyl-1-picrylhydrazyl (DPPH) EC50 of 57.6, 76.5, and 39.7 µg/mL and a ferric reducing antioxidant power EC50 of 84.8, 69.9, 41.2 µg/mL were determined for WE, EA, and Hy solution, respectively. The Rancimat induction time determined at 120°C in a lard sample with 200-ppm total phenol equivalent addition of WE, EA, and Hy was 8.92 h, 12.74 h, and 7.27 h, respectively (vs. 2.24 h for lard only). Extracts were added at the same dose (200 ppm) to minced beef patties that were put in closed containers under controlled air headspace composition (NA, natural air; HOA, modified air with 80% O2; and 20% N2) and stored at 4°C up to 10 days. Extracts showed significant effectiveness in contrasting decrease of O2 level in containers as well as pH and color changes of patties. A significant increase (expressed as mg of malondialdehyde MDA/kg; thiobarbituric acid-reactive substance (TBARS) assay was conducted in control samples at an interval of 0–10 days (from 0.52 to 0.78 mg of MDA/kg in NA samples; and from 0.55 to 1.31 mg of MDA/kg in HOA samples), while minimal changes were observed in treated samples. These findings suggest a potential use of OLEs for maintaining quality and oxidative stability of beef patties during storage.

Livestock Changes in Brazil and Sustainable Intensification Challenges

The increasing global demand for animal products has impacted Brazilian cattle farming. This study aims to offer references for developing more sustainable livestock farming in Brazil. It analyzes the numbers of pasture areas, cattle herds, and stocking rates from 1970 to 2017, based on agricultural census data. Additionally, it compares pasture conditions using agricultural census data and satellite imagery for the years 2006 and 2017. The key findings include the following: (1) a 119.7% increase in cattle herds, with migration from the South and Southeast to the North and Central–West regions, which have lower land prices; (2) a 2.6% decrease in the pasture area for cattle (except in the North region); (3) a 3.8% decrease in areas in poor condition; and (4) a 125.5% increase in the stocking rate. Despite technological advancements improving productivity, most pastures (59.6%) are still underperforming, indicating potential for reducing the pressure on native vegetation. This study concludes that production areas are shifting between regions in Brazil, with livestock farming intensifying, marked by a decrease in pasture areas and degraded pastures, alongside an increase in cattle numbers and stocking rates. However, these changes are heterogeneous across the country. This analysis provides an overview of beef cattle nationwide, which is relevant for addressing production sustainability challenges.

A preliminary report of integrating sheep farming in combination with adopting biogas technology in organic rice farming systems in upland areas in Indonesia

This study aims to understand the preliminary results of integrating sheep farming in combination with adopting biogas technology in organic rice farming (ORF) systems in upland areas. The research was conducted in upland areas in Grabag Subdistrict Magelang Regency, Central Java Province (UPL1) and Kertasari Subdistrict, Tasikmalaya Regency, West Java Province (UPL2), Indonesia. At each upland area, a demo plot with a 17 m3 digester has been established, and 120 sheep were introduced. A combination of sheep and beef cattle manure was used as a biogas substrate. The soil sample of one and three-year conversion of ORF was collected, and macro and micro minerals were analyzed. The biogas quality was analyzed, including dry matter (DM), nitrogen (N), carbon (C) and nitrogen-ammonia (N-NH3). The greenhouse (GHG) emissions, including methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O), were measured. The results indicated that C-organic content at three-year conversions of ORF in UPL1 was much lower (P<0.05) than the one-year conversion. The average CH4, CO2, and N2O contents in UPL1 were 661, 477.3, and 0.16 mg/m2/day, respectively. The average CH4, CO2, and N2O contents in UPL2 were 3328, 3038 and 2.42 mg/m2/day, respectively. In UPL1, the proportion of CH4 was 52.5 %, CO2 was 47.4 %, and N2O was 0.01 % while the proportion of CH4 was 57.9 %, CO2 was 42.0 %, and N2O was 0.01 % in UPL2. To conclude, integrating sheep farming in combination with adopting biogas technology in the ORF system improves manure management and provides organic fertilizer, which subsequently reduces the use of artificial fertilizer and avoids GHG emissions.v

Species Diversity and Seasonal Abundance of Stomoxyinae (Diptera: Muscidae) and Tabanid Flies (Diptera: Tabanidae) on a Beef Cattle and a Buffalo Farm in Nakhon Si Thammarat Province, Southern Thailand.

This study investigated species diversity and seasonal abundance of Stomoxyinae and tabanid flies, which are significant pests and vectors of animal pathogens, on a beef cattle and a buffalo farm in Nakhon Si Thammarat province, southern Thailand. During a one-year period from December 2020 to November 2021, flies were collected using Nzi traps from 6 a.m. to 6 p.m. over three consecutive days each month, resulting in the capture of 1912 biting flies, representing seven Stomoxyinae and nine tabanid species. The five most prevalent species were Tabanus megalops, Haematobia irritans exigua, Stomoxys calcitrans, Stomoxys indicus, and Stomoxys uruma. Fly density was notably higher on the beef cattle farm compared to the buffalo farm, with most species peaking during the rainy season, except for H. i. exigua, which was more abundant during the dry season. This study also examined the influence of temperature, relative humidity, and rainfall on fly density, revealing species-specific patterns. These findings offer updated insights into species diversity and seasonal trends, providing critical baseline data essential for the development of effective control strategies aimed at mitigating the impact of these flies on livestock health.

The Intersectionality Between Amazon and Commodities Production: A Close Look at Sustainability

Food production’s environmental, economic, and social challenges should be demystified through quantitative data. Therefore, the objective of this paper was to investigate the ecoregional sustainability of the Amazon biome from the perspective of the environmental life cycle, economic feasibility, and social life cycle analysis, emphasizing the pillars of sustainability in the production of three commodities: soybean, beef cattle, and Brazil nuts. Carbon footprint, net present value, and worker endpoint were the metrics evaluated. According to the results found in this study, the livestock presented greater environmental burdens in terms of carbon balance when compared to the production of Brazil nuts and soybean production with carbon balances in the order of 4.75 tCO2eq/ha, −0.02 tCO2eq/ha, and −1.20 tCO2eq/ha, respectively. From an economic viewpoint, the extractive production of Brazil nuts presented the highest net profit per hectare/year (USD 559.21), followed by the agricultural system (USD 533.94) and livestock (USD 146.19). Finally, in relation to the social aspect of the production systems analyzed, the negative impacts linked to beef cattle production are related to the subcategories of forced labor and equal opportunities, and the positive impacts linked to soybean production are related to the subcategories of salary and benefits. The results highlight a genuine and sustainable balance in Brazil nuts extraction, presenting it as an investment for a sustainable future while demystifying the multifaceted information related to food production as a whole, in order to assist in decision-making and the formulation of public policies.

Machine Learning for the Genomic Prediction of Growth Traits in a Composite Beef Cattle Population.

The adoption of genomic selection is prevalent across various plant and livestock species, yet existing models for predicting genomic breeding values often remain suboptimal. Machine learning models present a promising avenue to enhance prediction accuracy due to their ability to accommodate both linear and non-linear relationships. In this study, we evaluated four machine learning models-Random Forest, Support Vector Machine, Convolutional Neural Networks, and Multi-Layer Perceptrons-for predicting genomic values related to birth weight (BW), weaning weight (WW), and yearling weight (YW), and compared them with other conventional models-GBLUP (Genomic Best Linear Unbiased Prediction), Bayes A, and Bayes B. The results demonstrated that the GBLUP model achieved the highest prediction accuracy for both BW and YW, whereas the Random Forest model exhibited a superior prediction accuracy for WW. Furthermore, GBLUP outperformed the other models in terms of model fit, as evidenced by the lower mean square error values and regression coefficients of the corrected phenotypes on predicted values. Overall, the GBLUP model delivered a superior prediction accuracy and model fit compared to the machine learning models tested.

Using open-path dual-comb spectroscopy to monitor methane emissions from simulated grazing cattle

Abstract. Accurate whole-farm or herd-level measurements of livestock methane emissions are necessary for anthropogenic greenhouse gas inventories and to evaluate mitigation strategies. A controlled methane (CH4) release experiment was performed to determine if dual-comb spectroscopy (DCS) can detect CH4 concentration enhancements produced by a typical herd of beef cattle in an extensive grazing system. Open-path DCS was used to measure downwind and upwind CH4 concentrations from 10 point sources of methane simulating cattle emissions. The CH4 mole fractions and wind velocity data were used to calculate CH4 flux using an inverse dispersion model, and the simulated fluxes were then compared to the actual CH4 release rate. For a source located 60 m from the downwind path, the DCS system detected 10 nmol mol−1 CH4 horizontal concentration gradient above the atmospheric background concentration with a precision of 6 nmol mol−1 in 15 min interval. A CH4 release of 3970 g d−1 was performed, resulting in an average concentration enhancement of 24 nmol mol−1 of CH4. The calculated CH4 flux was 4002 g d−1, showing good agreement with the actual CH4 release rate. Periodically altering the downwind path, which may be needed to track moving cattle, did not adversely affect the ability of the instruments to determine the CH4 flux. These results give us confidence that CH4 flux can be determined by grazing cattle with low disturbance and direct field-scale measurements.

Brucellosis Seroprevalence in Cattle in China During 2014–2024: A Systematic Review and Meta-analysis

Brucellosis, caused by several species of Brucella, continues to be a significant illness that poses a global threat to public health. China remains a persistent hotspot for brucellosis, despite the implementation of extensive control measures. This study aims to conduct a systematic review and meta-analysis of the seroprevalence of bovine brucellosis in different breeds and regions of China from 2014-2024, and to provide predictions on the future prevalence patterns of brucellosis in cattle and humans. The analysis comprised a total of 80 research studies, which consisted of 187 datasets and a combined sample size of 3,130,706. We estimated the overall pooled seroprevalence of bovine brucellosis in China to be 1.5% (95% CI: 0.6-2.6%). Subgroup analysis revealed that the seroprevalence in dairy cattle was 3.1%, surpassing the seroprevalence in beef cattle (1.3%) and yak (1.5%). Regions that had authorized vaccination programs exhibited higher seroprevalence (1.8%) compared to regions that did not have vaccination (0.5%). Notably, the study observed a simultaneous rise in both the prevalence of brucellosis in cattle and the number of human brucellosis cases. This suggests that high-quality routine surveillance of brucellosis in cattle will be essential for predicting and responding to cases in humans. Additionally, given the existing prevention and control measures, brucellosis will likely continue to be prevalent in both cattle and people. This systematic review will assist policymakers in adjusting animal surveillance and interregional livestock movement policies, ultimately contributing to the public safety goal of preventing brucellosis in humans by controlling it in animals.

A review and future trends of precision livestock over dairy and beef cow cattle with artificial intelligence

Abstract The demand for meat and dairy products is expected to rise significantly in the current demographic and economic growth context. Concurrently, various factors, including financial crises and reduced profitability, have decreased the number of livestock farms. Consequently, the livestock industry is undergoing intensification, with an increased number of cows per farm. This shift makes the management of animals increasingly complex. Amid these challenges, the society’s growing concern for animal health and welfare and the quality of consumed products underscores the importance of systems that aid in the individual and herd-level monitoring and control within livestock operations. In this scenario, precision livestock farming has become essential with the emergence of new sensors and technologies and the evolution of artificial intelligence. Against this backdrop, this paper reviews systems and techniques used in precision livestock farming to detect anomalies caused by reproductive processes and diseases in dairy and beef cattle. The article analyzes sensors and technologies employed, presents key studies conducted, and discusses the most commonly used artificial intelligence techniques in detecting prevalent anomalies.

Assessment of the Intra- and Inter-Observer Reliability of Beef Cattle Mobility Scoring Performed by UK Veterinarians and Beef Farmers

Assessment of the Intra- and Inter-Observer Reliability of Beef Cattle Mobility Scoring Performed by UK Veterinarians and Beef Farmers

Comparative Genetic Study of Local and Introduced Cattle Breeds of Khizi District of Azerbaijan Republic

A comparative genetic study of local and introduced breeds of cattle in the farms of the Khizi district was carried out. Cattle of various breeds are kept on the territory of the region at enterprises of legal entities and individuals, in farms belonging to individual owners. Introduced breeds of cattle, beef and dairy cattle make up 0.0029% of the total livestock. Simmental (25%), Holstein-Frisian (27%), Brown Swiss (12%) and Aberdeen-Angus (7%) breeds are derived from introduced beef and dairy cattle. For a comparative study of the genomes of local and introduced breeds of cattle, blood samples were taken, DNA was obtained and prepared for further analysis.

The essential oil blend Agolin Ruminant L reduces methane production in vitro and in vivo when included in the drinking water of cattle.

Two experiments were conducted to determine the potential for the essential oil blend Agolin Ruminant L (Agolin) to reduce enteric methane (CH4) emissions from beef cattle when delivered via the drinking water. Experiment 1 evaluated aqueous solutions of Agolin (50mg/L) and a non-protein nitrogen and mineral solution (uPRO ORANGE [uPRO]; 1.7mL/L) individually and in combination, where Agolin was added to concentrated uPRO at 3, 4.5, 6% Agolin (w/w) prior to dilution with water at 1.7mL/L, for a total of five treatments. These were incubated for 48h with a medium-quality Rhodes grass (Chloris gayana) hay substrate, with gas production, CH4 concentration in gas, and digestibility measured in vitro. In Exp. 2, Droughtmaster steers (n = 24) were fed a basal diet of Rhodes grass hay and were allocated to one of three water treatments (n = 8/treatment) supplemented with either uPRO (2.27mL uPRO/L water), or one of two inclusion rates of Agolin in combination with uPRO (2.27mL uPRO and 6 µL Agolin/L water or 2.27mL uPRO and 24 µL Agolin/L water) with enteric CH4 emissions, feed and water intake, and live weight gain (LWG) measured over 56 d. In Exp. 1, the inclusion of Agolin in uPRO at 6% w/w resulted in a reduction in CH4 production (15.8%; P = 0.003) and the proportion of CH4 in the gas produced (24.5%; P < 0.001). In Exp. 2, steers consuming the lower quantity of Agolin via drinking water had a 16.4% (P = 0.0027) reduction in CH4 production over the experiment, declining from 140g/d during week 1 to 117g/d in week 8. This inclusion rate of Agolin in the drinking water also resulted in a 25g (17.6%) CH4/d decrease in emissions by steers compared to control steers (P = 0.0205). However, no significant differences in CH4 yield (g CH4/kg dry matter intake), or CH4 intensity (g CH4/kg LWG) by steers was observed between treatments. These results demonstrate that Agolin reduces CH4 emissions when mixed in aqueous solution under in vitro and in vivo conditions, providing a potential method to reduce enteric CH4 emissions from cattle in extensive production systems.

Impacts of Breed, Production System and Feeding Type on Nutritional, Organoleptic Characteristics and Oxidative Status on Beef Cattle in Sub-Saharan Africa: A Cross-Sectional Study

Purpose: The aim of this study was to investigate the influence of breed, production system, and feeding type on meat quality, evaluating organoleptic and physicochemical traits and antioxidant status across selected local cattle breeds. Materials and Methods: The study was carried out on sirloin and blood samples taken in slaughterhouses from the hot carcass of male cattle, divided according to breed, production system and type of feed. The nutritional, organoleptic characteristics and oxidative status was assessed. Findings: The results revealed that meat from Goudali breed raised in a sedentary system exhibited significantly lower tenderness (p&lt;.) and higher lipid (p&lt;.) and protein (p&lt;.) contents. Additionally, the meat displayed notably lower pH (p=.), reduced cortisol (p&lt;.), and lower catalase (p&lt;.), TAC (p&lt;.), and FRAP (p=.) activities. Consumers preferred the meat of the White Fulani breed due to its color (p&lt;.). In transhumant system, the meat was richer in dry matter (p=.), lipids (p&lt;.), and fibres (p=.), while the sedentary system resulted in more tender (p=.) and red-dark colored meat (p&lt;.), which consumers favored. Meat from cows under commercial feed were preferred by consumers (p&lt;.) compared to grass-fed cows, exhibiting significantly higher lipid (p&lt;.) and protein (p&lt;.) levels as well as intense color (p=.). However, meat from grass-fed cows had significantly higher fibre content (p&lt;.), tenderness (p&lt;.), better taste (p=.), juiciness (p=.), and higher catalase (p=.) and TAC (p&lt;.) activities. Implications to Theory, Practice and Policy: These findings underscore the importance of considering breed, production system, and feeding type when conserving, selecting, or improving beef breeds for both meat quantity and quality.

Genetic Perspectives on Feed Event, Meal and Feed Efficiency Traits in Bos taurus indicus Beef Cattle.

Electronic feeders record feeding behaviour as feed events by tracking the animal's in-out visits to the feeder. Another way to measure feeding behaviour is based on meals. However, the two approaches provide different outcomes. The objectives of this study were to estimate genetic parameters (heritabilities and genetic and phenotypic correlations) for feed event and meal traits, and their genetic and phenotypic correlations with feed efficiency traits in Nellore cattle. The present study analysed six feed event traits (DMIFE: dry matter intake per feed event, FED: feed event duration, TBFE: time between feed events, FTd: feeding time per day, FEd: feed events per day, and FR: feeding rate), six meal traits (DMIME: DMI per meal, MED: meal duration, TBME: time between meals, MC: meal criterion, MTd: meal time per day, and MEd: meals per day), and three feed efficiency traits (ADG: average daily gain, DMI, and RFI: residual feed intake). The traits were measured in feed efficiency tests of Nellore cattle (age = 280 ± 41 days and body weight = 258 ± 47 kg at enrolment). The MC was calculated for each animal and ranged from 1.70 to 64.0 min, i.e., any pair of feed events separated by less than the MC value was considered part of the same meal. The heritabilities and correlations were estimated by fitting univariate and bivariate animal models, respectively, using single-step genomic BLUP. The highest heritabilities for feed event traits were 0.35 ± 0.06 (FED), 0.39 ± 0.06 (FTd), and 0.50 ± 0.05 (FTd), and for meal traits were 0.31 ± 0.06 (MED) and 0.45 ± 0.06 (MTd). The genetic correlation between feed event traits and meal traits were weak. FR, FED, and FTd had moderate genetic correlations with RFI (-0.56 ± 0.11, 0.44 ± 0.11, 0.60 ± 0.08, respectively). These results indicate that more efficient animals spent less time at the feeder per feed event and per day, and eat faster compared to less efficient animals. In conclusion, feed event and meal traits must be treated as distinct groups of traits since the genetic and phenotypic correlations were, in general, weak to moderate. Among feed event versus meal traits, feed event traits are more favourable to explain the genetic relationships of feeding behaviour with feed efficiency-related traits.

Histopathologic and ultrastructural findings in oak (Quercus spp.) toxicity on 2 beef cattle farms in Colorado.

Natural oak toxicity, a phenomenon sporadically reported in the United States, is due to consumption of any part of most oak trees (Quercus spp.). Ruminants, mainly cattle, are disproportionately susceptible to oak toxicity. Toxicity is attributed to degradation of the oak plant hydrolysable tannins by rumen microbes and enzymes into absorbable low-molecular-weight metabolites, which are postulated to bind and damage endothelial cells by unknown mechanisms. The clinical manifestations of acute toxicosis are nonspecific or broadly suggestive of renal disease due to acute tubular injury. Here we document the clinical, gross, histopathologic, and novel ultrastructural features of natural acute oak nephrotoxicity in 3 beef calves on 2 farms in Colorado, USA. Gross postmortem findings included perirenal edema with renomegaly and hemorrhagic gastroenteritis. Histologically, renal tubular epithelial necrosis was severe, with hemorrhage and intratubular hyaline casts. Transmission electron microscopy revealed extensive involvement of proximal and distal convoluted tubules, with predominantly intact basement membranes, and glomerular and interstitial endothelial injury and necrosis. The ultrastructural details of toxic nephropathy and vasculopathy induced by oak metabolites in natural cases of bovine oak toxicosis have not been described previously, to our knowledge.